sci.physics.particle

On Fri, 16 Nov 2007 09:55:56 +0100, chilldown wrote:

> Thanks Jim,
>
> The equation of the propagator is as follows:
> Its in Euclidean space.
>
> Int(d^4k * exp(i*k*x)/ (k^4 +m^2 +i*epsilon).
>
> I have Peskin and Zee but cannot find the justification of adding i-epsilon
> except that its added to make it integrable.
>
> I would like to keep the poles on real axis and avoid the poles by excluding
> them through
> closing the countor without them therefore avoiding the i-epsilon.

I think you mean (k^2 +m^2 +i*epsilon).

In either case, if this is in a 4-D Euclidean space, there are no poles on
the real axis here unless m=0 [although there are poles at
k_0 = +/- i*sqrt(m^2 + k_1^2 + k_2^2 + k_3^2)].

--
Jim E. Black